This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The focus of our structural studies on the 70S ribosome is to obtain high resolution structures of different functional complexes corresponding to different states of the ribosome during translation. Ribosome complexes containing various combinations of mRNA, tRNAs, translational factors and other ligands are being constructed and crystallized for structural analysis. Our ultimate goal is to assemble the resulting structures into a high-resolution 'movie'that will provide a description of translation as it occurs on the ribosome.